FWIW...
....my power toys primarily live in Los Anchorage. Typical winter sees regular below 0 (F) temps, frequent below -10, and often quite a few days of -20.
....For the boat and the OR Jeep and the summer ATV, I pull the batteries and put them inside; fully charged in circa October / November; trickle charged to full charge about 1x per month after that until "spring" which realistically means mid-May.
....For the spare road vehicles, I typically end up moving them around the driveway at least 1 x per month, so nothing special is done to the batteries, although I make sure the engine runs at least 45 mins during that 1x per month.
....For the PA-12 and the sno-go; trickle charge about 1x per month if not otherwise used; on the infrequent trip to cold country (where -30 is common, -50 is not unheard of), I pull the batteries every night and bring them in the tent/cabin, etc. Particularly when flying the PA-12 somewhere cold, if it doesn't start one is either faced with a very serious situation or faced with the need to hand prop...a very serious PITA.
My batteries typically last at least 8-10 years, but they're all automotive, not golf cart.